HashMap in java

In the Previous post, we have learnt about TreeSet in java. In this post, we will learn HashMap in java.

HashMap has the following features.

• HashMap implements Map Interface and extends AbstratMap class.
• It stores the data in the form of Key and value pair.
• It contains only unique elements.
• It may have one null key and multiple null values.
• It does not maintain an order.

What is difference between HashSet and HashMap?

HashSet contains only values whereas HashMap stores data in form of key and value.

Let’s understand HashMap in details.

• Add elements to HashMap
• Iterate Over HashMap
• Sort HashMap on the basis of keys and values
• Remove key and value pair from HashMap